As electronic equipment is miniaturized, the storage, handling, and transport of electronic components become more important. Generally, the electronic components are transported to an assembly location in a carrier tape assembly that has a plurality of pockets formed therein to hold the electronic components. The carrier tape assembly includes a carrier tape and a cover tape or film. Carrier tapes are often manufactured in a thermoforming or embossing operation in which a web of thermoplastic polymer is delivered to a mold that forms the component pockets in the carrier tape. A cover film can be heat sealed continuously along the edges of the carrier tape to seal the electronic components within the pockets of the carrier tape.
The electronic components are mounted onto a printed circuit board (PCB) or other substrate during assembly of electronic equipment or sub-assemblies that will be used later to build electronic equipment. The cover film is removed from the carrier tape during this assembly process to expose the electronic components residing within the pockets of the carrier tape. The component is typically lifted from a pocket by automatic precision placement machines and mounted to the PCB or substrate being assembled.
However, as semiconductor or other electronic components become smaller and thinner, the electronic components can migrate out of the pocket during shipping and handling FIGS. 1A and 1B show how electronic devices can migrate out of the pocket of two styles of conventional carrier tapes.
FIG. 1A shows a conventional carrier tape assembly 100 including a carrier tape 102. Carrier tape 102 includes central portion 105 extending longitudinally along the length of the carrier tape and two side portions 104, 106, each side portion disposed on opposite sides of the central portion and extending longitudinally therewith. The central portion has a plurality of pockets 112 formed therein. The side portions are disposed on opposite sides of the central portion and extend longitudinally therewith. In addition, each of the side portions includes a row of aligned advancement structures 108 and 110 such that the advancement structures extend along the edges of the carrier tape. The side portions and central portion are flat and lie in the same plane.
Carrier tape 102 may be formed of any polymeric material that has a sufficient thickness and flexibility to permit it to be wound about the hub of a storage reel. A variety of polymeric materials may be used including, but not limited to, polyester (e.g., glycol-modified polyethylene terephthalate), polycarbonate, polypropylene, polystyrene, polyvinyl chloride, and acrylonitrile-butadiene-styrene.
Carrier tape assembly 100 typically further includes an elongate cover film 120 applied over the pockets of carrier tape 102 to retain electronic components therein. As illustrated, cover film 120 includes parallel longitudinal bonding portions 122, 124 that are bonded to top surface of side portions 104,106, respectively, of the carrier tape. For example, a pressure sensitive adhesive such as an acrylate material, or a heat-activated adhesive such as an ethylene vinyl acetate copolymer, can be used to adhere the cover film to top surface of side portions 104, 106.
Because the bonding portions 122, 124 are spaced away from the edges 113, 114 of the pockets 112 formed in the central portion of carrier tape 102, the electronic devices, such as electronic device 130, can migrate out of the pocket during shipping and handling. When this occurs, the electronic devices can pop off of the carrier tape when the cover film is removed and be lost.
FIG. 1B shows an alternative conventional carrier tape assembly 200 has a strip portion 202. Strip portion 102 includes central portion 205 having a plurality of pockets 212 formed therein and an elevated land portion 209 between adjacent pockets along the length of the central portion of the carrier tape, two side portions 204, 206, the side portions are disposed on opposite sides of the central portion and extending longitudinally therewith, and a row of aligned advancement structures 210 formed in side portion 206.
Carrier tape 100 typically further includes an elongate cover film 220 applied over the pockets of the strip portion to retain electronic components therein. As illustrated, cover film 220 includes parallel longitudinal bonding portions 222, 224 that are bonded to longitudinal top surfaces of edge portions 104,106 of strip portion 102.
Because the bonding portions 222, 224 are spaced away from the edges 213, 214 of the pockets 212, the electronic devices such as electronic device 230, can migrate out of the pocket during shipping and handling When this occurs, the electronic devices can pop off of the carrier tape when the cover film is removed and be lost.